Arsenal faces Champions League challenge without a traditional striker

• William Gallas warns Arsenal about playing without a striker in the Champions League.
• PSG has won two European crowns without a traditional No.9.
• Arsenal signed Viktor Gyokeres for a significant fee to address their striker issue.
• Gyokeres scored 21 goals in his debut season but has not fully convinced all stakeholders.
• Arsenal aims to make European history as Premier League title holders.